Grease a 9-inch square (or 10-inch round) metal cake pan. Set aside.
Add chopped dates and baking soda to a medium bowl. Pour in the boiling water and stir. Let stand until completely cooled.
In a large bowl with an electric beater or in the bowl of a stand mixer, beat the butter and 1 cup brown sugar until light and smooth. Beat in the egg, then the vanilla.
In a separate medium bowl, whisk together the flour, baking powder, nutmeg and salt. Add the flour mixture to the butter mixture, alternating with date mixture, making 3 additions of flour mixture and 2 of date mixture.
Spoon batter into prepared pan and smooth top. Bake in preheated oven until firm to a light touch and a tester inserted into centre comes out clean, about 30-35 minutes. Remove from oven and switch oven broiler on.
Start the topping when the cake is almost done. Combine 1/2 cup brown sugar, butter, cream and coconut in a heavy saucepan. Bring to a boil over medium heat, then reduce heat and boil gently for 1 minute. Spread topping mixture evenly over hot cake.
Broil cake about 6 inches from the heat source until bubbling and golden brown, about 1 to 2 minutes. **Don't wander off! Watch closely as topping can burn quickly.
Remove from oven and let cake cool on rack until cooled completely.
This cake keeps well at room temperature for several days or you can freeze to enjoy later.Be sure to read the "Cook's Notes" in the original post, where I share some valuable tips, options, substitutions and variations for this recipe!